The present invention relates to self-sealing injection buttons for medical devices such as inflatable devices which are designed to be implanted in the body and then inflated in situ by introduction of a hypodermic needle or the like. Such injection buttons are also usable in permanently or semipermanently implanted devices for drug administration.
For example, Edmunds et al, U.S. Pat. No. 3,831,583 shows an implantable bulb designed for use with a blood vessel constricting device. In this prior art device, the injection button comprises a silicone gel filled elastomeric bulb adapted to be pierced by a hypodermic needle for introduction of an inflating fluid. Upon withdrawal of the needle the gel flows to seal the puncture hole.
While such devices are functional they are relatively expensive to manufacture and there is at least some small danger of the gel being forced from the bulb in the event of extreme pressure within the device, especially if a tear should propagate in the thin rubber shell due to piercing.
Other devices designed for similar purposes exist in the prior art and include gels, thick soft rubber sections or valves designed for introduction of a tubular device for introduction or withdrawal of liquid materials. Such devices are designed to be used on inflatable mammary prostheses, blood vessel restricters, and drug injection systems, for example. A need continues to exist, however, for an economical device which offers more positive sealing after puncture.